I’d hate to call it deceptive, since that’s a term used by the FTC and other government outfits to call out shady companies doing less than kosher things. So that may be a bit harsh.

But I would define some of the mortgage advertising out there as slightly “misleading.”

You see, there are ads, whether they’re in your local newspaper, on a billboard, at a bus stop, or online, which advertise a “low fixed rate” on your mortgage.

Unfortunately, many of these aren’t really fixed-rate mortgages. In fact, they’re quite the opposite.

Your Fixed-Rate Mortgage Is an ARM

Say what? That’s right. These seemingly fixed-rate mortgages are often adjustable-rate mortgages, otherwise known as ARMs, and also referred to as “exploding ARMs” by those who got burned by interest rate resets.

You see, somewhere along the way mortgage lenders got the bright idea that they could advertise super low mortgage rates on popular 30-year mortgages by exploiting the amortization period.

Most mortgages, whether they’re truly fixed for the life of the loan or adjustable, have a 30-year term.

So a 5/1 ARM is still a 30-year mortgage, but the mortgage rate is only fixed for the first five years before becoming annually adjustable for the remaining 25.

This makes it a so-called “hybrid ARM,” because it has both a fixed and adjustable-rate component during the mortgage term.

A 30-year fixed mortgage, on the other hand, has an interest rate that’s fixed for 30 years. That means the mortgage rate never changes. Ever.

As a result, you would expect the hybrid ARM to come cheaper than the 30-year fixed for that future interest rate uncertainty.

And indeed, the 30-year fixed is currently pricing around 4%, while the 5/1 ARM is pricing around 3%, per the latest Freddie Mac data.